FIG. 5 is a general block diagram of a conventional angular velocity sensor. As shown in FIG. 5, conventional angular velocity sensor 50 includes vibrator 51, driving circuit 52 for driving vibrator 51, and sensing circuit 55 for sensing angular velocity Ω given to vibrator 51.
Vibrator 51 vibrates by being given drive signals from driving electrodes 51c and 51d, and outputs sense signals with phases opposite to each other generated based on angular velocity Ω given from the outside, to sensing electrodes 51a and 51b, respectively.
Driving circuit 52 outputs drive signals, which are generated by amplifying a signal having been input from monitor terminal 52c, from drive terminals 52a and 52b. 
Sensing circuit 55 converts sense signals having been input from sensing terminals 55a and 55b to voltage signals using current-voltage converters 55c and 55d; differentially amplifies the signals using differential amplifier 55g; senses angular velocity Ω using sensing circuit 55; and then outputs the velocity to output terminal 55i. 
Angular velocity sensor 50 is configured so that a vibration signal from vibrator 55f can be input to current-voltage converter 55c through switch 55e. Further, sensor 50 includes disconnection sensing circuit 55j that outputs a signal indicating whether abnormality is present or not based on a signal from sensing circuit 55h to disconnection sensing terminal 55k. 
To sense abnormality with this configuration, switch 55e is turned on and disconnection sensing circuit 55j monitors a DC fluctuation value to sense abnormality of angular velocity sensor 50.
There is known patent literature 1 for example as information on prior art documents related to the invention of the application.
However, for conventional angular velocity sensor 50 to sense abnormality, switch 55e needs to be turned on, which prevents the sensor from sensing abnormality while being used as an angular velocity sensor.
Signal line 54a connecting sensing electrode 51a with sensing terminal 55a, and signal line 54b connecting sensing electrode 51b with sensing terminal 55b are easily disconnected. However, conventional angular velocity sensor 50 is unable to sense a disconnection in signal lines 54a and 54b. 